If you were wrongfully convicted of a crime, how would you fight the system? 16-year-old Arthur Carmona and his mom, Ronnie Sandoval, spent years doing just that.

"He wanted to fight. He said, 'I'm not signing shit. If I can't prove I'm innocent then I'm going to die in here,'" says Ronnie of her son. She fought tirelessly to get Arthur out of prison after he was wrongfully convicted of 12 counts of armed robbery.

"I'm disgusted with what they did to my son," Ronnie says, "it was as simple as him walking out the door to go play video games and he stepped into the Twilight Zone, and it followed him for all the days of his life."

How did Arthur get thrown in prison for a crime he didn't commit? Rob Warden, director of Northwestern University's Center on Wrongful Convictions, says it's not uncommon.

"Every case that we look at is different," says Warden, "but there are common elements and there are things that seem to transcend them." Warden helped develop a project to raise awareness about wrongful convictions, and bring about change. The National Registry of Exonerations was released earlier this year and documents over a thousand cases of exonerations in the US.

"Our great hope for the registry is [that it will] provide data that will fortify arguments for reform," Warden says.

The registry also provides reasons why the exonerees were wrongfully convicted such as false confessions, errors with eyewitness testimony and a phenomenon called "tunnel vision."

"It's very difficult to exonerate someone," Warden says, "you find that once you are convicted of a crime, the evidence that it takes to exonerate you just has to be far greater than the evidence that it took to convict you in the first place."

Yet Warden hopes the registry will highlight these systemic problems with the justice system and help free the wrongfully convicted still behind bars.

About 8 minutes.

Written and produced by Tracy Oppenheimer. Camera by Paul Detrick and Zach Weissmueller.